Conventionally, 2D (two dimensional) detector is known as an X-ray detector used in an X-ray CT apparatus. A 2D detector is an X-ray detector whose plural X-ray detection elements are two-dimensionally arranged in the channel (ch) direction and the row direction. According to a 2D X-ray detector, imaging of a wide range can be performed.
X-ray detection data detected by each X-ray detection element of an X-ray detector are output to a data acquisition system (DAS) as electrical signals. In the DAS, digitized projection data corresponding to each X-ray detection element are generated by signal processing, such as amplification, integration processing, A/D (analog to digital) conversion processing, and logarithmic transformation processing, of the X-ray detection data. In a typical X-ray CT apparatus, an X-ray detector and a DAS are integrated and installed in a rotating part of a gantry, as a data detection system.